1. Field of the Invention
The present invention relates to antennas, and more particularly towards a dual-band antenna for mobile computer devices.
2. Description of Prior Art
Typically, a wired cable is used by a laptop to communicate with another processing device such as another laptop, desktop, server, or printer. To communicate without a wired connection, an antenna is needed. FIG. 1 shows two possibilities of outside antennas. Antennas can be located at the top of a laptop display 100 for better radio frequency (RF) clearance, or just outside (dash line for antenna) of a Personal Computer Memory Card International Association (PCMCIA) card 101. Usually, the laptop will have an optimum wireless performance if the antenna is mounted on the top of the display 100. However, an external antenna will generally be more expensive and susceptible to damage than an internal antenna. Alternatively, an internal or embedded antenna generally will not perform as well as an external antenna. The commonly used method to improve the performance of an embedded antenna is to keep the antenna away from any metal component of the laptop. Depending on the design of the laptop and the type of antenna, the distance between the antenna and metal components could be at least 10 mm. FIG. 2 shows some possible embedded antenna implementations. Two antennas are typically used, though applications implementing one antenna are possible. In one case, the two antennas are placed on the left 200 and right 201 edge of the display. Using two antennas instead of one antenna will reduce the blockage caused by the display in some directions and provide space diversity to the communication system. As a result, the size of the laptop becomes larger to accommodate antenna placement. In another configuration, one antenna can be placed on one side (200 or 201) of the display and a second antenna on the top 202 of the display. This latter antenna configuration may also provide antenna polarization diversity depending on the antenna design used.
Advances in wireless communications technology are developing rapidly. The 2.4 GHz Instrument, Scientific, and Medical (ISM) band is widely used. As an example, many laptop computers will incorporate Bluetooth technology as a cable replacement between portable and/or fixed electronic devices and IEEE 802.11 b technology for wireless local area networks (WLAN). If an 802.11 b device is used, the 2.4 GHz band can provide up to 11 Mbps data rate. For higher data rates, the 5 GHz Unlicensed National Information Infrastructure (U-NII) band can be used. U-NII devices can provide data rates up to 54 Mbps. As a result, the demand for a dual-band antenna operating at both bands is increasing. Dual-band antennas with one feed have some advantages over multi-feed antennas for cellular applications.
As wireless communications among processing devices become increasingly popular and increasingly complex, a need exists for a compact integrated dual-band antenna having reduced costs and reliable performance.
The present invention relates to an antenna for integration into a portable processing device. According to one aspect of the invention, the antenna includes an electronic display metal support frame for grounding a conducting element, a first and a second radiating element extending from the support frame, and a conductor for conducting a signal comprising a first component for carrying a signal connected to the second radiating element and a second component for grounding the conducting means connected to the support frame.
The first and second radiating elements are concentric with the first radiating element disposed within the second radiating element. The first radiating element is one of an inverted-L antenna and a slot antenna.
The second radiating element is one of an inverted-F antenna and a slot antenna.
An impedance match is achieved by positioning a feed conductor towards a midpoint of the length of the second radiating element for increasing impedance at a lower band and towards a closed end of the length for decreasing the impedance at the lower band.
Preferably, the means for conducting the signal is a coaxial cable having an inner feed conductor connected to the second radiating element and an outer conductor connected to the support frame.
The first and second radiating elements are disposed substantially along a plane of the support frame. The first and second radiating elements are substantially transversely disposed on the support frame.
The antenna includes a duplexer connected to two communications systems and the dual-band antenna for transmitting at two bands simultaneously.
According to an embodiment of the present invention, an integrated antenna arrangement is provided including a conductive RF shielding foil disposed on the back of an electronic display having an integrated dual-band antenna, and a feed portion extending partially across a hole forming a slot antenna.
The antenna arrangement further includes means for conducting a signal comprising a first component for conducting the signal connected to the feed portion and a second component for grounding the conducting means connected to the RF foil opposite the feed portion.
The means for conducting the signal is a coaxial cable having an inner conductor connected to the feed portion and an outer conductor connected to the RF foil opposite the feed portion.
An impedance match is achieved by positioning a feed conductor towards a midpoint of the length of the antenna arrangement for increasing impedance and towards an end of the length for decreasing the impedance.
Preferably, the antenna arrangement further comprises means for conducting a signal comprising a first component for conducting the signal connected to the feed portion and a second component for grounding the conducting means connected to the RF foil opposite the feed portion. The means for conducting the signal is a coaxial cable having an inner conductor connected to the feed portion and an outer conductor connected to the RF foil opposite the feed portion.
An impedance match is achieved by positioning a feed conductor at an open end of the length of the antenna arrangement for increasing impedance and towards a closed end of the length for decreasing the impedance electronic display metal support frame for grounding a conducting element, a pair of radiating elements extending from the display frame, and a means for conducting a dual-band signal comprising a first component for carrying a signal connected to the first and second radiating elements and a second component for grounding the conducting means connected to the display frame.